The purpose of this project is to examine irregular monoterpene biosynthesis in plants as a model for more clearly defining the mechanism of head-to-head condensations (squalene synthesis). This approach will greatly simplify the synthesis of potential intermediates and should facilitate an enzymological study of this process. Initially, plants of the Compositae family will be screened for high yield production of irregular monoterpenes. When a suitable plant is found, it will be used as a source for the development of a cell-free terpene enzyme system. Potential intermediates will be synthesized and used as substrates in the cell-free system in order to define the mechanistic pathway. On the basis of successful model studies analogous triterpene intermediates will be synthesized and investigated as presqualene intermediates.